Various types of pressure sensing systems for monitoring the pressure within the tires of an automotive vehicle have been proposed. Such systems generate a pressure signal using an electromagnetic (EM) signal which is transmitted to a receiver. The pressure signal corresponds to the pressure within the tire. When the tire pressure drops below a predetermined pressure, an indicator is used to signal the vehicle operator of the low pressure. Many vehicles require different tire pressures in the front of the vehicle and the rear of the vehicle. Therefore, it is important to know the relative position of the pressure sensor and thus the tires relative to the vehicle.
The National Highway Traffic Safety Administration is requiring a phase in of tire pressure monitoring systems in vehicles. Tire pressure monitoring systems are used on passenger vehicles and heavy-duty vehicles. In order to maintain the pressure measurement tolerance required to meet regulatory requirements, the tire pressure sensor has to be calibrated with respect to the target application. Typically, this means passenger vehicles and heavy-duty vehicles require different pressure sensors. However, requiring different pressure sensors increases the overall cost to the manufacturer.
It would therefore be desirable to automatically adjust the tire pressure sensor calibration to the applied pressure so that a single tire pressure sensor may be used for different applications.